Patent GB-1437944-A (GB)
Title: Explosive jointing of submerged tubular members
IPC: B23K20/08
Filed: 1973-01-29
Abstract: 1437944 Welding by pressure; jointing by tube expanding INTERNATIONAL RESEARCH & DEVELOPMENT CO Ltd 29 June 1973 [21 June 1972 29 Jan 1973] 29128/72 and 4455/73 Headings B4J and B3R In explosively forming a joint between first and second tubular members submerged in a liquid, the end of the first member is arranged inside the end of the second member with a space therebetween, an explosive charge is disposed within the end of the first member, shock-absorbing and liquid displacing elements are disposed in the two members with seals to form a sealed enclosure the liquid is displaced from the enclosure by a gaseous medium and the charge is detonated. The joint may be a mere expansion joint or a weld. In an embodiment a reduced diameter end 12a, Fig. 1, of a metal sleeve 12 is fusion welded at 13 or explosively welded to a metal pipe 11 and a metal pipe 10 is located on the sea-bed in the reduced diameter other end 12b of the sleeve so that an annular space 14 is provided between the end of the pipe 10 and the inner surface of the sleeve 12, the overlapping parts of the pipe and sleeve being abraded. An inflatable bag 15 and an inflatable sealing bag 16 are inflated in the pipe 11 before insertion of the pipe 10 in the sleeve and an inflatable bag 17 with an explosive carrying inflatable body 18 are inflated in the pipe 10 again before insertion of the pipe 10 into the sleeve 12. A rubber sealing ring 19 has a flap 20 which is rolled over the sleeve end 12b to form an external seal and inlet and outlet ducts 22 and 23 pass through the sleeve into the space 14. Clean air or nitrogen is supplied from the surface through duct 22 to expel water in the sleeve 12. The sleeve is then flushed with fresh water, air or nitrogen, methylated spirits and finally dried air or nitrogen. A clamp 24 is placed about the sleeve and the charge is detonated possibly by a switch device operated by a magnetic field. In a modification the sleeve is replaced by a belled end of pipe 11 and the end of the pipe 10 is advanced to engage within a step formed in the pipe 11 between the belled end and the normal diameter portion. An inflatable seal is placed between the pipe 10 and the step instead of the seal 16. In an embodiment of a repair of an underwater pipe 20, Fig. 3, by attachment to it of a sleeve 31 having a pipe coupling annular flange 32 the end of the pipe 30 is introduced into the sleeve 31 through a flared guiding start 33 on a lip 34 welded to the end of the sleeve 31. An inflatable seal 35 is arranged between the pipe and the lip 34 and is inflated through a pipe 36. An inflatable seal 37 is located at the end of the pipe against the sleeve 31, the seal 37 being supported by a ring 38 which supports an inflatable explosive charge 39, A clamp ring 41 is clamped by an expanding clamp 41 within the sleeve and springs 42 press on the ring to urge the ring 38 towards the pipe 30 to hold the seal 37 in place. The charge 39 is retained by a cover plate 45 containing a radial initiating charge and a detonator 46 and is inflated by a tube 47 led through apertures 48 in the plate 45. An inflatable bag 50 is located within the pipe 30 and bears against a spacer 51 and a clamp 52 is arranged about the sleeve 31. Water is removed from the space 54 between the pipe and sleeve as before and the bore of the ring 40 and ring 38 are foam filled or air bagged and the charge is detonated. The rings 38 and 40 may be of plastics which break under the explosive forces.